Dear Hamish,
Yes, the lines are absolutely horizontal - every point has the same elevation. I tried v.to.db before writing to the list. But v.to.db only has options to upload the following values: cat, area, compact, perimeter, length, count, coor, start, end, sides, query, slope. A v.what query on a typical line has:
Map: con10
Mapset: PERMANENT
Type: Line
Line: 2110
Length: 432.740896
Line height: 200.000000
Layer: 1
Category: 2110
Driver: mysql
Database: sardisutm
Table: con10
Key column: cat
cat : 2110
type : 4
level : 3
graphicgroup : 0
colorindex : 3
weight : 0
style : 0
entitynum :
mslink :
text :
I tried just typing "line height" into v.to.db anyway, but got a predictable error
ERROR: value <line height> out of range for parameter <option>
Legal range: cat,area,compact,perimeter,length,count,coor,start,end,sides,query,slope
I just figured out that you can get the information from v.out.ascii, and then discard the coordinates and such; but it seems like there should be an easier way of accessing this information.
Many thanks!
Nick Cahill
On Nov 28, 2008, at 7:14 PM, Hamish wrote:
Nick wrote:
I have a series of contour vector maps imported from a CAD
program (Microstation). The CAD maps were in 3d, and the 3d
information was successfully imported into GRASS, so the
vectors have line heights as well as length, etc. Now I need
to export these into shapefiles. When I do this, all the
other useless CAD data like line color, style, weight, etc.
is exported as attributes in the .dbf file, but line height
is not -- it is not a field in the mySQL database but is
part of the geometry of the line, if I understand what's
going on here correctly. Is there a way to transfer line
height into the attribute table so I can access and export
it? Many thanks,v.db.addcol + v.to.db ?
note that unless lines are perfectly horizontal (eg elevation contours)
you can not assign a single elevation value to a line's attributes (as
each vertex will have its own value, and the attribute is associated with
the line as a whole), so I would expect in general for it to refuse to try.as for 3D shapefile export, ummm... check the wiki, help pages, and ML
archives. It rings a bell but I've no idea how.Hamish